Update About

About.md

@@ -19,7 +19,7 @@ where $`\lambda`$ is electron wavelength, $`CL_{eff}`$ the effective detector ca
 Electron probe grows in size with induced defocus accordingly to the probe semi-angle. For proper reconstruction, the probe has to fit into \textit{probe window.} Maximum defocus which fits into the window is given by
 
 ```math
-\Delta f_{max} = \frac{w_{semi}  - r_{0}}{\tan \alpha_{corr}} [to test]
+\Delta f_{max} = \frac{w_{full}/4}{\tan \alpha_{corr}} [to test]
 ```
 
 where $`w_{semi}`$ is probe semi-window, $`r_{0}`$ the beam radius with 0 defocus and $`\alpha_{corr}`$ the real probe semi-angle.